Effect of phenytoin therapy on thyroid function.

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Finucane JF, Griffiths RS

Effect of phenytoin therapy on thyroid function.

Br J Clin Pharmacol. 1976 Dec;3(6):1041-4. doi: 10.1111/j.1365-2125.1976.tb00355.x.

PubMed ID

22216527 [ View in PubMed

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Abstract

Serum total and free fraction of thyroxine and triiodothyronine and urinary losses of unconjugated hormones in normal subjects and in patients treated long-term with therapeutic doses of phenytoin have been measured. Decreases in serum total hormone concentrations with increased free fractions and resultant significant increase in the concentration of free thyroxine but not triiodothyronine were apparent in phenytoin-treated subjects. However, serum free hormone concentrations remained within the euthyroid range. These changes in serum free hormone concentration were reflected by an increased urinary loss of unconjugated thyroxine, but normal excretion of unconjugated triiodothyronine. Phenytoin in therapeutic doses displaces thyroxine and to a lesser extent, triiodothyronine from binding proteins in serum and thus increases peripheral clearance of thyroid hormones.

DrugBank Data that Cites this Article

Drug Carriers

Drug	Carrier	Kind	Organism	Pharmacological Action	Actions
Phenytoin	Thyroxine-binding globulin	Protein	Humans	No	Substrate	Details